Primefree sequences in the OEIS. A bad idea.
Antti Karttunen
antti.karttunen at gmail.com
Mon Oct 24 09:51:28 CEST 2005
N. J. A. Sloane wrote:
>Concerning this:
>
>
>Sequence An in Sloane's Online Encyclopedia of Integer Sequences
>contains no primes.
>
>THIS IS REALLY ill-defined! There are two interpretations:
>A_n as visible in the current OEIS contains no primes
>or
>A_n when considered in full - meaning usually all infinitely
>many terms - contains no prime
>
>Only the second version is at all interesting, but I'm afraid
>it was the former that was calculated. Does anyone know?
>
>
>
and Jud McCranie wrote:
At 11:00 PM 10/21/2005, franktaw at netscape.net wrote:
> > The next terms are 132,141,143,144,145,152,156,173,252 (if I did not
> make a mistake).
> >There are no others up to 287; I was unable to determine whether
> A000287 contains any primes,
> > partly because its definition is unclear.
> Is 882 in the sequence? What about 2967? Or 3828?
Just for these reasons, I think these kind of sequences open
a big can of worms, even without any Cantorisms.
Next someone comes up with a sequence "those n for which sequence An
in OEIS contains no integers of the form 17k+-3". " or "... no integers with
palindromic (decimal) expansion." Would anybody like to edit and check
these?
Terveisin,
Antti
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